1. Technical Field of the Invention
The invention relates generally to communication systems; and, more particularly, it relates to compensating for undesired amplitude modulation, such as may be caused by an interference source, within such communication systems.
2. Description of Related Art
Data communication systems have been under continual development for many years. Generally speaking, within the context of communication systems that employ various types of communication devices, there is a first communication device at one end of a communication channel with encoder capability and second communication device at the other end of the communication channel with decoder capability. In many instances, one or both of these two communication devices includes encoder and decoder capability (e.g., within a bi-directional communication system). Transferring information from one location to another can be applied generally within any type of communication system, including those that employ some form of data storage (e.g., hard disk drive (HDD) applications and other memory storage devices) in which data is processed and/or encoded before writing to the storage media, and then the data is processed and/or decoded after being read/retrieved from the storage media.
Certain communication systems employ one or more of various types of coding (e.g., error correction codes (ECCs) whose decoding may be performed iteratively) to ensure that the data extracted from a signal received at one location of a communication channel is the same information that was originally transmitted from another location of the communication channel. Communications systems with iterative codes are often able to achieve lower bit error rates (BER) than alternative codes for a given signal to noise ratio (SNR).
In addition, various types of communication systems may employ one or more of various types of signaling (e.g., orthogonal frequency division multiplexing (OFDM), code division multiple access (CDMA), synchronous code division multiple access (S-CDMA), time division multiple access (TDMA), etc.) to allow more than one user access to the communication system. Such signaling schemes may generally be referred to as multiple access signaling schemes.
In accordance with processing signals transmitted across a communication channel within such communication systems, one function that is oftentimes performed is that of channel estimation. From certain perspectives, channel estimation (sometimes alternatively referred to as channel detection, channel response characterization, channel frequency response characterization, etc.) is a means by which at least some characteristics of the communication channel (e.g., attenuation, filtering properties, noise injection, etc.) can be modeled and compensated for by a receiving communication device. While the prior art does provide some means by which channel estimation may be performed, there is an ever-present need for better and more efficient channel estimation approaches that intrude as minimally as possible in the maximum and overall throughput that be achieved for signals transmitted across a communication channel within a communication system.